The present invention relates to a spring-loaded joint sealing key assembly for providing sealing pressure between joint seal faces.
In a turbine assembly, there are several locations where spring-loaded sealing key assemblies are required to eliminate or minimize leakage paths between mating faces of a joint. For example, generally semi-circular arcuate upper and lower casings are joined one to the other along a horizontal midline and it is necessary to provide a seal along a potential midline leakage path. For some mating parts, there is insufficient space on the joint to place an existing screw-type spring-loaded assembly because of adjacent machining and/or parts. Solid staked sealing keys have been used where the joint space is scarce. Further, the small scale of conventional sealing assemblies renders the assembly and verification of dimensional requirements difficult, the dimensional requirements being necessary to effect a reliable seal. This problem is compounded when manufacturing in large numbers.
Large screw retained spring-loaded assemblies have also been used as joint sealing key assemblies where joint space is readily available. Particularly, multiple retaining screws are typically installed through the sealing key face and into a slot machined into the joint to be sealed using tapped holes. In joint sealing assemblies of this type, highly accurate detailed measurements are taken to ensure that the sealing key face is sufficiently raised above the joint to be sealed so that when the joint is assembled, the opposing part halves displace the sealing key fully into the key slot. The sealing force is provided by leaf-type springs located under the sealing key. The screws, however, must prevent the sealing key assembly from falling out of the joint during assembly while also affording adequate clearance for sealing key movement. Thus, each screw must be located so that its head lies below the joint interface. Otherwise, the joint parts cannot fully mate. While this joint sealing key assembly is effective, it is difficult to manufacture and install because of the tight tolerances, as well as the intense labor necessary to install the parts.
In accordance with a preferred embodiment of the present invention, there is provided a spring-loaded joint sealing key assembly available for use where joint space is inadequate for conventional screw-type assemblies or is adequate and a key assembly of the present type is desired. The present sealing key minimizes or eliminates needs for preassembly of the sealing key to joint measurements. Drilling and tapping screw holes in a side of one of the joint parts also eliminates any holes formed in the contact face of the sealing key and eliminates retaining screw hole to key wall tolerance considerations. Particularly, the present invention provides a joint sealing key assembly including a generally oblong shaped sealing key with one or more multiple dowel posts projecting from the key in a direction opposite from the sealing key face. Each dowel post has an oblong hole opening laterally generally parallel to the seal face of the parts. Retaining pins, preferably spring dowels, are receivable through holes in the sides of the joint extending generally parallel to the sealing key face for registration with the oblong hole through the post. Further, the underside of the sealing key has a recess for receiving a spring, preferably a leaf spring.
One of the joint parts includes a key slot generally conforming to the peripheral shape of the sealing key. Clearance holes are drilled into the bottom surface of the key slot to provide an opening for receiving the posts of the sealing key. It will be appreciated that the apertures receiving the spring dowels are formed in registration with the oblong holes opening laterally through the key posts. The depth of the key slot is also formed to fully accommodate the depth of the sealing key.
To install the sealing key, the leaf springs are placed into the sealing key slot at a location out of registry with the holes for the posts. The sealing key is then placed into the sealing key slot, resting on the springs in an uncompressed position. The spring dowels are then placed into the dowel apertures and translated longitudinally to engage the post holes on the sealing key. It will be appreciated that the dowels retain the sealing key in an uncompressed condition in the key slot during assembly. Upon assembly of the joint halves, the sealing face of the sealing key is engaged by the sealing face of the other part and the sealing key is displaced into a final compressed position within the key slot. Thus, the sealing face of the sealing key and the seal face of the adjoining part form a seal.
In a preferred embodiment according to the present invention, there is provided a joint sealing key assembly comprising first and second parts having respective joint seal faces, the first part having a slot opening through the joint seal face thereof, a joint sealing key receivable in the slot and having a sealing face and a recess along a side thereof remote from said sealing face, the joint sealing key including a hole opening laterally through one side thereof, a spring in the recess and cooperable between the joint sealing key and the first part for biasing the joint sealing key in a direction toward the second part, the first part having at least one aperture opening laterally into the slot and in alignment with the hole in the joint sealing key when the joint sealing key is received in the slot and a pin received through the aperture and in the hole for retaining the joint sealing key in the slot with the spring biasing the sealing face of the joint sealing key into sealing engagement with the seal face of the second part.
In a further preferred embodiment according to the present invention, there is provided a joint sealing key assembly comprising first and second parts having respective joint seal faces, the first part having a slot opening through the joint seal face thereof, a joint sealing key receivable in the slot and having a sealing face, the joint sealing key including a hole opening laterally through one side thereof, a spring cooperable between the joint sealing key and the first part for biasing the joint sealing key in a direction toward the second part, the first part having at least one aperture opening laterally into the slot and in alignment with the hole in the joint sealing key when received in the slot, the hole having an extent in a direction toward the second part greater than an extent of the aperture in the direction and a pin received through the aperture and in the hole for retaining the joint sealing key in the slot while enabling the spring to bias the joint sealing key for movement in the direction to sealingly engage the sealing face of the joint sealing key with the seal face of the second part.